AQUEOUS PIGMENT DISPERSION, AND AQUEOUS INK FOR INKJET RECORDING

PROBLEM TO BE SOLVED: To provide an aqueous pigment dispersion which has a small volume-average particle diameter and excellent discharge stability and from which an aqueous ink for inkjet recording is obtained.SOLUTION: The aqueous pigment dispersion contains a carbon black pigment, a urethane poly...

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Hauptverfasser: HATA TOMOHITO, KASAI AKIRA, ITOTANI KAZUO
Format: Patent
Sprache:eng ; jpn
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Zusammenfassung:PROBLEM TO BE SOLVED: To provide an aqueous pigment dispersion which has a small volume-average particle diameter and excellent discharge stability and from which an aqueous ink for inkjet recording is obtained.SOLUTION: The aqueous pigment dispersion contains a carbon black pigment, a urethane polymer having an anionic group, a water-soluble solvent and/or water. WhenH-NMR of a 1 wt.% aqueous solution (A) of the urethane polymer having the anionic group is measured, the area of a peak which is observed at around 4.0 ppm and is derived from the methylene adjacent to a urethane bond is defined as (A1) and whenH-NMR of another solution (B) is measured, which solution is obtained by mixing a pigment in the 1 wt.% aqueous solution of the urethane polymer so that a weight ratio of the urethane polymer to the pigment becomes 1/4, the area of another peak which is observed at around 4.0 ppm and is derived from the methylene adjacent to the urethane bond is defined as (B1). The area (A1) and the area (B1) satisfy a relationship of the inequality (1). The aqueous ink for inkjet recording is obtained by using the aqueous pigment dispersion.SELECTED DRAWING: None 【課題】 体積平均粒径が小さく吐出安定性に優れたインクジェット記録用インクを与える水性顔料分散体を提供する。【解決手段】 カーボンブラック顔料と、アニオン性基含有ウレタンポリマーと、水溶性溶媒及び/または水とを含有し、前記アニオン性基含有ウレタンポリマーが、該ウレタンポリマーの1重量%水溶液(A)の1H−NMRの測定により得られた4.0ppm付近に観察されるウレタン結合に隣接したメチレンに由来するピーク面積(A1)と、該ウレタンポリマーの1重量%水溶液に顔料を該ウレタンポリマーの重量/顔料の重量が1/4となるように混合した溶液(B)の、1H−NMRの測定により得られた4.0ppm付近に観察されるウレタン結合に隣接したメチレンに由来するピーク面積(B1)とが、式(1)の関係を満たす水性顔料分散体、及び該水性顔料分散体を使用するインクジェット記録用水性インク。【数1】(1)【選択図】 なし